1. Laboratory of Bioinorganic Chemistry, Department of Agro-Environmental Science and Technology, University of Bologna, Viale Giuseppe Fanin 40, 40127 Bologna, Italy, Department of Chemistry, University of Siena, Via Aldo Moro 2, 53100 Siena, Italy, Department of Chemistry, University of Firenze, Via della Lastruccia 5, 50019 Sesto Fiorentino, Italy, and CERM (Center for Magnetic Resonance), Via Luigi Sacconi 6, 50019 Sesto Fiorentino, Italy